Oil-proof flame-resisting conduit, cable, etc., and method of making same



1932- J. A. KENNEDY 1,844,324]

OILPROOF FLAME RESISTING CONDUIT, CABLE, ETC. AND METHOD OF MAKING SAME Filed 001?. 8, 1928 Patented Feb. 9,1932

UNITED stares J'QSEBE A. KENNEDY,OF PAWTUOKEI', RHODE ISLAND, ASSIGNOE, BY ASSIGN- HINTS, 1'9 ANACONDA. WIRE AND CABLE COMPANY, A CORPORATION OF DELAWARE OIL-PROOF FLAME-EEBIBTING OONDUTIT, CABLE, nrc.,nrm TRUE GB G can Application med October 8, 1928. Eerie! Kc. $11,259.

The present invention relates to fiexihle pitch coating oi cable or conduit makes the non-metallic conduit for receiving and protesting the msulated wires of electric light and power circuits, and to the insulated conductors and cables of such circuits, in buildings and other situations where protection-against mechanical injury, fire, water, and other injuries liable to cause a short circuit, is important. Among other circumstances in which such protection is valuable, is use with'the electrical equipment of automobiles, the wires of which are, in service, liable to conditions which would cause rapid deterioration if not guarded against, such as wetting with lubricatingoil, gasolene and water, impact of grit and water "driven by the wind or the splash of the wheels, and so forth. Hence the wires for this. and other purposes where oil may be encountered, re quire protection from oil as well. as from fire and water. Within the meanin of the word oil as used in this specification to define the quality of protection given bv articles embodying the present invention, include gasolene and other so-callcd light oils, as well as lubricating oil, grease, etc.

It has been the object of this invention to provide protection for electrical conductors combining immunity from access of oil to the rubber insulation with resistance to fire and to penetration of water to the conductors. In carrying (out this object I have utilized lacquers containing cellulose derivatives as the oil-proofin agent in combination with the flame-proo ng and water-proofiing. agents heretofore generally used in the product of commercial protected electrical cable and conduit for electrical conductors.

-One phase of the invention resides in such coating tacky.

Hence order to produce the first phase or feature of the invention, above mentioned, I was confronted with the problem of so applying the lacquer that the final coated article would not be sticky. I have solved this problem in two ways, both embodying the same generic invention, which constitutes the second phase of the present invention. One consists in applying thelacquer in two or more coats with a curing period between the first and second coats, as hereinafter more particularly described. The other consists in applying an intermediate coat or film of a difiFerent substance, as silicate of soda, be-

tween the stearin pitch surface and the lac-- quer coating.

Before describing the invention in further detaihl would say that the articles or manulectures treated according to this invention are single insulated conductors having an outer braided or woven sheath or jacliet, cable consisting of two or more conductors arranged side by side. and all enveloped by a braided or woven jacket, an open woven tuhe of suitable structure and character to serve the uses of electric conduit, and the like structures; all being lrnown in the art. The treatment according to the invention involves an effect onlvon the outer sheath or jacket such conductors or cables, and on the elec trical conduit. inasmuch as such conduit is itself a sheath or jacket, didering from the sheath of a cable or conductor principally in that it is originally completed apart from the wires which it is intended to embrace,

instead ot being manufactured directly upon them, the entire class of manufactures to which the invention is applicable may be comprehensively considered and designated embodying this invention; and

Fig. 2 isa similar view of anelectrical conduit illustrating another embodiment of the invention. I

The cable of Fig. 1 consists'of two or more electrical conductors, each provided with its own insulating and protective covering, of any suitable character,and both envelo ed by a braid or woven sheath a compose of cotton or other suitable porous strands. 1) represents a flameroofing coating preferably of stearin pitcli, as usual, deposited on the sheath (1. c is a sealing coat or layer, of suitably a 'ed cellulosic lacquer or dried silicate of so a enveloping the coat 6, as hereinafter more fully described. d is the final or finishing layer of cellulosic lacquer enveloping the intermediate layer 0.

In the second embodiment of the invention, shown in Fig. 2, the numeral 1 represents a conduit made preferably as a seamless woven tube of strands having suitable qualities for articles of this class, the nature of which is well understood by those acquainted with this art. 6, c and d are coatings of the same nature and applied in the same sequence as above described in connection with Fig. 1.

It is to be understood that the terms coat,

terial to the present invention. Neither is the number of such substances and the number of coatings or impregnations in which the substances are applied; nor the identity of the substances themselves, except as to that phase of the invention which involves a particular mode of pplying cellulosic lacquer upon stearin pitc It is suiiicient that before being treated with lacquer, the sheathing has been treated, according to practices well known and long used, or otherwise, soas to be resistant to penetration by water and to combustion when exposed to flame in suitable measure to meet the requirements of the service for which it is designed. The article ma have both a water-proofing compound an a flame-proofing compound, or a fiameproofing compound alone. If treated with stearin pitch as the flame-proofing substance, it may or may not be provided with a coating or impregnation of water-proofin agent beneath the stearin pitch coating. 11 ractice,

however, commercially salable con uit and.

sheathed conductors of this class must have fireand water-resistingproperties sufiicient to-comply with the standards established by the National Board of Fire Underwriters.

The lacquer which I use inoil-proofing sheathing of the character here defined com-' prises a cellulose compound or derivative as x a base mixed with a suficient quantity of solvents to make the solution freel fluid, and a. content of castor oil or equiva ent miscible.

emollient a nt to make the dry residue of the lacquer exible. I have used and may use various commercial lacquers of which the base is either nitrocellulose or cellulose acetate and the solvents are any substances having adequate solvent action. As between lacquers which have greater or less inflammability, I prefer to use those which are less inflammable; although the quantity of cel-' lulose compound le t after drying of the lacquer onthe sheathingis sothin and'has such small mass that it does not cause-a fire hazard even when having ahighly inflammable composition, becauseit develops too little heat 1n lburning to afiect the fire-proofing mate-. r1a

The solvents (acetone, amyl acetate, the ketones, etc.) which have the most active solvent action on the cellulose com ounds, and one or more of which practical y must be used in making the lacquer and thinning One of'the met ods by which I overcome this unavoidable ill efiect is to subject the article, after its first treatment of lacquer, to a curing or aging ste by which the sticky surface is solidified. 'i he agin step may be performed variously. In practice I prefer to carry it out by first passing the lacquer coated goods through a heated oven or curing chamber through which a circulation of air is maintained and then exposing them to the open air for about three hours. The oven is heated to a temperature of about 180 F. and the goods are passed through at a rate which causes any given oint to remain in it for about two minutes. ide variations are possible in these particulars, however, for the temperature may be an? ing between about 150 F. and about 300 and the time of heat curing slightly less or considerably more than two minutes; provided that, if the tem erature is high enough 'to melt stearin itcli, the goods must not be exposed to it ong enough to soften the pitch envelope. Such forced curing is valuable in that ,it causes a glossy surface to be developed'on the lacquer. Air laden with the vapor of the solvents is continuously withdrawn from the oven and fresh heated airsubstituted. The subsequent air curing period need not continue for as longas three hours, but may i be as short as one hour. On the other hand, it may be much longer than three hours with good effect on the product, but considerations of cost require limitation to about the time stated during working hours, or to over-night periods in the case of goods lacquered at the end of the working day. Generally, although not necessarily, two coats are applied and aged in this way, and two outer coats afterwards applied; although the invention includes a single sealing coat, or more than two, and any number of outer coats, of lacquer.

Thus the stearin pitch element of the article is sealed in and safeguarded against attack by the solvents in a subsequent coat or coats of lacquer.

An alternative mode of protecting the stearin pitch element for the same purpose is to apply a coat of sodium silicate or equivalent solution which will adhere to and dry on stearin pitch, and to which cellulose lacquer will in turn adhere without dissolving it.

After the coating of stearin pitch has been thus sealed and protected by either of the means above described, any desired number of additional or top coats of lacquer may be applied in a similar way. At the conclusion of the process the surface of the coated article is smooth and glossy and possesses substantially perfect impermeability by oil and water. The surface film is tough, flexible and elastic, but not sticky. Thus the finished product is water-proof, oil-proof and flameproof, and is adapted to serve the purpose of protecting electrical wires from in ury by these agencies. The toughness andflexibility of the coating protects the article also against abrasion and damage by the impact of flying particles of sand, etc. in circumstances where it is exposed to the impact of such particles.

What I claim and desire to secure by Letters Patent is:

1. An oil-proof and flame-proof insulated electrical conductor, cable, conduit, and the like. having an envelope of stearin pitch as its flame-proofing element and having also a sealing coat over said envelope and an outer film of dried cellulose lacquer over said sealing coat.

2. The method of covering a stearin pitch coated article with a solution of cellulose derivative having as the solvent a substance which is also a solvent of stearin pitch, which consists in first sealing the surface of the stearin. pitch coating against attack by the solvent in the after-applied solution, and then applying a top coat of said solution.

3. The method of covering a stearin pitch coated article with cellulose derivative dissolved in a solvent which has also solvent effect on stearin pitch, comprising first covering the stearin pitch coating with such S0111? tion, then dryin the film of applied solution, and finally app ying a top coat of the same solution.

4. The improvement in the method of covering a stearin pitch surface with cellulose lacquer dissolved in a liquid which is also a solvent for stearin pitch, which consists in applying and drying a sealing coat on the stearin pitch surface to protect it from attack by the solvent in the lacquer, and subsequently applying the surface film of lacquer.

5. The method of oil-proofing a stearin pitch coated article which consists in applying cellulose lacquer to the surface of such article, drying the lacquer, and applying a top coat of lacquer over the dried surface thereof.

6. The method of making non-sticky on the surface a sheathing of the character specified which has been provided with a flameprooting coat of stearin pitch, which consists in covering the stearin pitch coat with cellulose lacquer, aging the lacquer coat by subjecting the coated goods to heated dry air at a temperature between 150 F. and 300 F. and further exposing the oods to the open air for a period in the neigh liorhood of three hours, andthen applying a top layer of cellulose lacquer and drying the same.

In testimony whereof I have aflixed my signature.

JOSEPH A. KENNEDY. 

